Adding Custom Classes to bootstrap rows and cols

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Hi is there any way to target bootstrap row or col divs to add classes to these?

example:
<div class="col-sm-9 myClass">
content 
</div>

instead of:
<div class="col-sm-9">
<div class="ccm-custom-style-interface19 myClass">
content 
</div>
</div>


There are so many flexbox classes that could be added to columns, that predefining presets for each in the theme.php are not really a viable option.
Thanks.